The cell-surface-expressed nucleolin is associated with the actin cytoskeleton
The cell-surface-expressed nucleolin is associated with the actin cytoskeleton
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DOI：
10.1006/excr.2000.5071
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发表时间：
2000-12-15
影响因子：
3.7
通讯作者：
Krust, B
中科院分区：
文献类型：
--
作者：
Hovanessian, AG;Puvion-Dutilleul, F;Krust, B
核仁蛋白是一种结合RNA和蛋白质的多功能蛋白。核仁蛋白主要是一种核仁蛋白，在不同类型的细胞表面以及细胞核和细胞质内的胞内池中持续表达。通过共聚焦和电子显微镜使用特异性抗体对抗核蛋白，我们发现细胞质核蛋白是在小泡中发现的，这些小泡似乎将核蛋白转运到细胞表面。在低温或无血清培养基中，核蛋白的易位明显减少，而传统的细胞内糖蛋白转运抑制剂没有作用。因此，核蛋白的易位是通过一种独立于内质网-高尔基复合体的途径进行主动转运的结果。当核蛋白特异性单克隆抗体mAb D3交联时，细胞表面表达的核蛋白聚集在质膜的外侧。这种聚集，发生在20度和组织良好的模式，是依赖于一个完整的肌动蛋白细胞骨架的存在。在37℃时，mAb D3被内化，从而说明表面核蛋白可以介导特定配体的细胞内输入。我们的研究结果指出，核蛋白也应该被认为是细胞表面的一个组成部分，在那里它可以作为各种配体的细胞表面受体发挥作用。(C) 2000年学术出版社。
Nucleolin is a RNA- and protein-binding multifunctional protein. Mainly characterized as a nucleolar protein, nucleolin is continuously expressed on the surface of different types of cells along with its intracellular pool within the nucleus and cytoplasm. By confocal and electron microscopy using specific antibodies against nucleolin, we show that cytoplasmic nucleolin is found in small vesicles that appear to translocate nucleolin to the cell surface. Translocation of nucleolin is markedly reduced at low temperature or in serum-free medium, where as conventional inhibitors of intracellular glycoprotein transport have no effect. Thus, translocation of nucleolin is the consequence of an active transport by a pathway which is independent of the endoplasmic reticulum-Golgi complex. The cell-surface-expressed nucleolin becomes clustered at the external side of the plasma membrane when cross-linked by the nucleolin-specific monoclonal antibody mAb D3. This clustering, occurring at 20 degreesC and in a well-organized pattern, is dependent on the existence of an intact actin cytoskeleton. At 37 degreesC, mAb D3 becomes internalized, thus illustrating that surface nucleolin can mediate intracellular import of specific ligands. Our results point out that nucleolin should also be considered a component of the cell surface where it could be functional as a cell surface receptor for various Ligands reported before. (C) 2000 Academic Press.